Download Florida`s Introduced Birds: Sacred Ibis

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WEC267
Florida's Introduced Birds: Sacred Ibis (Threskiornis
aethiopicus)1
Steve Johnson and Monica McGarrity2
Many non-native birds have been introduced in
Florida—perhaps as many as 200 species! Of these,
at least 16 introduced species are considered
established, according to various authorities, and
some are now considered invasive and could have
serious impacts in Florida. This fact sheet introduces
the Sacred Ibis, and is one of a series of fact sheets
about Florida's established non-native birds and their
impacts on our native ecosystems, economy, and the
quality of life of Floridians. For more information on
Florida's introduced birds, how they got here, and the
problems they cause, read "Florida's Introduced
Birds: An Overview"
(http://edis.ifas.ufl.edu/UW297) and the other fact
sheets in this series,
http://edis.ifas.ufl.edu/
topic_series_floridas_introduced_birds.
Species Description
The Sacred Ibis (Threskiornis aethiopicus) is a
member of the ibis and spoonbill family
(Threskiornithidae). Birds in this family are wading
birds with long, downward-curved bills that they use
to probe in mud or grass for invertebrates and other
prey. Sacred Ibises are larger than Florida's native
ibises. Adults are approximately 30 inches long (75
cm) with a wingspan of 44–49 inches (112–124
cm) and weigh about 3 pounds (1.4 kg). Sacred Ibises
(Fig. 1) have mostly white bodies and wings; the
trailing edges of their wings (tips of the feathers) are
gray-black. They have very distinctive long, black
feathers or plumes on their rumps (Fig. 1). During the
breeding season the feathers on the sides of their
chests and on the outer wings (near the edge when
folded) may have a yellowish (or reddish) tinge, and
their lower legs may be tinged with reddish-copper;
bare patches of scarlet-red skin may also be visible
under their wings. The heads and necks of young
Sacred Ibises are covered with black and white
feathers, giving the head and neck a mottled
appearance (Fig. 2); these feathers are lost as the
birds mature. The heads and necks of adults are bare
of feathers and are gray-black, as are their long,
curved bills, legs, and feet. Sacred Ibises are quiet
birds and lack distinctive calls.
1. This document is WEC267, one of a series of the Wildlife Ecology and Conservation Department, Florida Cooperative Extension Service, Institute of Food
and Agricultural Sciences, University of Florida. Original publication date October 2009. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.
2. Steve A. Johnson, assistant professor and Extension specialist, Department of Wildlife Ecology and Conservation and Gulf Coast Research and Education
Center, University of Florida/ IFAS—Plant City Center, 1200 North Park Road, Plant City, FL 33563; Monica McGarrity, biological scientist, Gulf Coast
Research and Education Center, University of Florida/ IFAS—Plant City Center, 1200 North Park Road, Plant City, FL 33563
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and
other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex,
sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service,
University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie FerrerChancy, Interim Dean
Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.
Florida's Introduced Birds: Sacred Ibis (Threskiornis aethiopicus)
Figure 1. The Sacred Ibis (Threskiornis aethiopicus) is
similar in appearance to native ibises, but is much larger.
This invasive bird also looks very similar to the native
Wood Stork. However, the bill of the Sacred Ibis is more
slender and curved; the head, neck, bill, legs, and feet are
much darker black; and it has long black plumes on its
rump. Credit: Richard Mittleman (www.gon2foto.com),
2006 Credits:
Figure 2. Juvenile Sacred Ibises are similar in appearance
to adults, but their heads and necks are covered with black
and white feathers. This gives the head and neck a mottled
appearance, making it easy to confuse young birds with
endangered native Wood Storks. However, even young
Sacred Ibises have the characteristic black plumes on their
rumps. Credit: Helen Harris, Kenya Birds
(www.kenyabirds.org.uk), 2009 Credits:
Figure 3. The White Ibis (Eudocimus albus) is smaller than
the invasive Sacred Ibis, and is nearly solid white with a
reddish bill, legs, and feet. The head and neck are covered
with white feathers. Only the tips of the wings are black,
and the black wing tips are usually hidden unless the bird is
in flight. Credit: Steve A. Johnson, University of Florida,
2005 Credits:
Figure 4. The endangered Wood Stork (Mycteria
americana) is larger than the Sacred Ibis, and the head,
neck and bill are much lighter and marked with gray and
tan. Notice that the black outer feathers of the wings can
be seen even when the wings are folded. Credit: Steve A.
Johnson, University of Florida, 2005 Credits:
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Florida's Introduced Birds: Sacred Ibis (Threskiornis aethiopicus)
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Similar Species
Sacred Ibises are somewhat similar in
appearance to the native White Ibis (Eudocimus
albus), but are larger. Adult White Ibises (Fig. 3) are
approximately 22–27 inches (56–68 cm) long,
weigh about 1.5–2.5 pounds (750–1,050 g), and
have a wingspan of only 38 inches (96.5 cm). The
feathers of White Ibises are mostly white—only the
three feathers at the tips of their wings are tipped with
black. They also have feathered white heads and their
bills, legs, and feet are an obvious reddish-pink, not
black like those of Sacred Ibises. During the breeding
season, White Ibises' reddish bills are tipped with
black.
Sacred Ibises look very similar to the native
Wood Stork (Mycteria americana), a member of the
stork family (Ciconiidae) that is federally listed as an
endangered species. Wood Storks (Fig. 4) are larger
than Sacred Ibises, and have a more erect body
posture when resting than ibises (Fig. 5). Wood
Storks also have lighter-colored heads and necks with
grayish or tan markings (Fig. 4). Young Sacred Ibises
(Fig. 2) look especially similar to Wood Storks, due
to the mottled appearance of the black and white
feathers on their heads and necks. However, the bills
of Wood Storks are mostly straight and only the
lower third of the bill curves downward (Fig. 5A);
ibis bills form a long, continuous curve (Fig. 5B &
C). Wood Stork bills are mostly brown, and only the
base of the bill is black; Sacred Ibises have solid
black bills. Wood Storks also lack the characteristic
black plumes seen on the rumps of Sacred Ibises.
Resting Wood Storks can also be identified by their
black outer (primary) feathers (the edges of their
wings are black), which are visible even when their
wings are folded (Fig. 4).
All three of these species look very similar when
viewed from the underside as they fly overhead.
Sacred Ibises have white wings with a black trailing
edge (Fig. 6A); during the breeding season they may
also have bare patches of scarlet skin under the
leading edge of the wing. Adult White Ibises have
nearly solid white wings with black tips (Fig
6B).Wood Storks have much more black on their
wings—all of the outermost feathers are black (Fig
6C).
Figure 5. Native Wood Storks (A) have a much more erect
stance when seen in silhouette, and only the tip of the bill
is curved. Sacred Ibises (B) and native White Ibises (C)
both have bills that are curved along the entire length and
have similar silhouettes, but invasive Sacred Ibises are
much larger than the native ibis. Credit: Florida Fish and
Wildlife Conservation Commission, 2009 Credits:
Figure 6. The patterns on the undersides of their wings
can be used to identify invasive Sacred Ibises in flight.
Sacred Ibises (A) have white wings with a black trailing
edge, and may have patches of bare, scarlet-red skin
under the leading edges of the wings during the breeding
season (stippled black when viewing in black-and-white).
White Ibises (B) have nearly solid white wings with black
tips. Endangered Wood Storks (C) have white wings with
black outer feathers. Credit: Monica McGarrity, University
of Florida, 2009 (Modified from basic bird wing outline by
Muriel Gottrop, Wikimedia Project, 2008) Credits:
Native Range and Habitats
Sacred Ibises are native to sub-Saharan Africa,
the Middle East, and Madagascar; historically, they
were also found in Egypt, where they are now extinct.
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Florida's Introduced Birds: Sacred Ibis (Threskiornis aethiopicus)
These large birds are often depicted in Egyptian
hieroglyphs as the earthly representation of the god
Thoth (also shown as an ibis-headed man) and were
considered sacred—hence the common name. They
are very similar in appearance and so closely related
to the Black-headed Ibis (T. melanocephalus) in
South Asia and the Australian White Ibis (T.
molucca) that many scientists consider the three a
"superspecies," and some believe they may actually
all be the same species. In their native range, they
inhabit coastal estuaries, lagoons, marshes, and other
inland wetlands such as flooded agricultural fields
and urban retention ponds.
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found in close proximity to urban areas, especially
waste management dumps, golf courses, and urban
lakes. Although introduced Sacred Ibises have only
been found in southern Florida, scientists believe that
the flexible habitat requirements of this species could
allow them to expand their range to include other
areas of Florida. Identifying and reporting the
presence of these invasive birds is extremely
important, so that scientists can capture and remove
them and thus prevent these birds from becoming
established and spreading. For more information on
efforts to control Sacred Ibises in Florida, see the
"Solutions" section below.
Mode of Introduction
The widespread destruction caused by Hurricane
Andrew in 1992 resulted in the accidental release of
many species of non-native wildlife in Florida,
including Sacred Ibises. It is believed that the Sacred
Ibises found living in the wild in Florida have
descended from animals that escaped during this
natural disaster. Five individuals escaped from the
Miami Metro Zoo during or after the hurricane, but
remained near the zoo. Although these animals were
seen breeding nearby in the following years, the zoo
was able to capture and remove young birds from the
nests before they could disperse. However, the
number of Sacred Ibises seen near the zoo gradually
increased, suggesting that Hurricane Andrew may
also have resulted in the escape of additional birds
from private bird collections in the Miami area.
Introduced Range and Habitats
In the United States, introduced Sacred Ibises
have only been found in areas of southern Florida
(Fig. 7), including Everglades National Park and the
Arthur R. Marshall Loxahatchee National Wildlife
Refuge. Escapes from zoos have also resulted in the
introduction of Sacred Ibises in many parts of
Europe. There are now established breeding colonies
in Spain, France, Italy, Belgium, the Netherlands, and
Germany.
Introduced Sacred Ibises can inhabit a wide
variety of wetland and upland habitats, including
coastal estuaries, lagoons, and marshes; inland
wetlands and marshes; agricultural fields (flooded or
not); and urban retention ponds. They are usually
Figure 7. Approximate United States range of the
introduced Sacred Ibis (Threskiornis aethiopicus). Credit:
Monica McGarrity, University of Florida, 2009 (Data
source: Everglades Cooperative Invasive Species
Management Area) Credits:
Ecology
The diet of Sacred Ibises is broad and includes a
wide variety of prey items. The generalist diet of this
species may help it to successfully invade and survive
in new areas. Sacred Ibises often forage in groups of
2–20 individuals, using their long, curved bills to
probe mud or grass for prey or scavenge for scraps in
garbage. They will eat virtually anything that
moves—insects, worms, crayfish, mollusks, other
invertebrates, small fish, amphibians, and small
rodents. Sacred Ibises can also prey on the eggs and
nestlings of other birds, especially seabirds. In
addition, in urban areas they are often found near
trash heaps, where they eat a variety of scraps and
other refuse.
Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.
Florida's Introduced Birds: Sacred Ibis (Threskiornis aethiopicus)
Like many wading birds, Sacred Ibises roost in
trees at night, often in large groups of hundreds of
birds, sometimes with birds of other species. Sacred
Ibises are usually the last birds to arrive at roosts each
evening, often showing up well after sunset. They
breed near their foraging and roosting grounds, and
may nest individually or build large, communal
platforms of sticks that hold as many as 30 nests.
Each pair builds a nest of twigs, in which the female
lays 2–3 eggs. The eggs hatch in 28–29 days, and
the young remain in the colony for an additional
44–48 days; both the male and female care for the
eggs and young birds. In the Everglades, Sacred
Ibises roost and nest on tree islands, often among
native species.
Ecological Impacts
Sacred Ibises are one of only a few species in the
bird Order Ciconiiformes (herons, storks, ibises,
spoonbills) that prey on the eggs and nestlings of
other birds. In their native range in Africa, Sacred
Ibises eat the eggs of seabirds, including gulls, terns,
cormorants, pelicans, and gannets. In their native
range, Sacred Ibises take enough eggs and young
from one Cape Cormorant (Phalacrocorax capensis)
colony each year that they are considered one of the
leading causes of mortality of these imperiled birds.
Scientists studying seabird colonies in Europe have
also found that predation by introduced Sacred Ibises
is a significant problem.
We know very little about the impacts of Sacred
Ibises in Florida. In Europe, Sacred Ibis populations
have been known to grow exponentially, increasing
their numbers from hundreds to thousands within five
to ten years. Without aggressive, concentrated
eradication efforts by wildlife professionals (see
"Solutions" below), these large birds could proliferate
and might eventually have negative impacts on our
native species. Most importantly, Sacred Ibises in
Florida nest in the same areas (and even in the same
colonies) as endangered Wood Storks, and could
prey on their eggs and young. Although Sacred Ibises
in Florida have not been reported nesting with
seabirds or preying on their eggs or young, Florida is
also home to several threatened seabird species. If
Sacred Ibises were allowed to become established
and proliferate, they could cause harm to these
species as well.
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Impacts on People and Pets
The impacts of invasive Sacred Ibises on humans
would likely be minimal. Like all birds, ibises can
carry a variety of disease-causing agents (bacteria,
viruses, etc.) that can spread to humans, so their feces
could pose a health risk. Sacred Ibises often forage in
human garbage for scraps, and could become a
nuisance if populations were allowed to become
established.
Solutions
Local governments (e.g., Palm Beach County),
Florida Fish and Wildlife Conservation Commission
(FWC), and the United States Department of
Agriculture Wildlife Services Office
(USDA/APHIS/WS) have teamed up to attempt to
eradicate invasive Sacred Ibises. At this time, experts
believe that all Sacred Ibises living in the wild in
south Florida have been removed—approximately 75
birds total. Scientists are cautiously hopeful that the
Sacred Ibis has proven to be a "success story" for
invasive species management, and that these invasive
birds may have already been eradicated. Efforts to
manage Sacred Ibises and other invasive birds have
gained increasing support from conservation
societies, including the Florida Audubon Society,
because of the serious threat that they pose to native
species. Florida's citizens can also play an important
role in efforts to manage invasive birds. For more
information on what you can do, see "How you can
help" below.
How You Can Help
You can help to manage invasive species by
becoming part of Florida's invasive species detection
and rapid response network. Use the tips in this fact
sheet to learn to identify Sacred Ibises, and keep your
eyes open—especially in southern Florida! If you
think you have spotted a Sacred Ibis, try to take a
photo so that wildlife biologists can use it to confirm
your sighting, and report it immediately. Never try to
capture or kill a bird you think is a Sacred Ibis, since
you could accidentally harm an endangered, native
Wood Stork. Eradication is best left to professional
wildlife removal experts.
Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.
Florida's Introduced Birds: Sacred Ibis (Threskiornis aethiopicus)
Sacred Ibises have been found at several sites
across south Florida (shown in Fig. 8), and all known
individuals have been removed, so it is especially
important to report sightings in new locations. You
should immediately report the number of birds and
their exact location to the FWC by contacting Larry
Connor (e-mail: [email protected]; Phone:
(352) 357-2398). If possible, please e-mail digital
photos of the birds along with your report, or contact
Larry Connor for a mailing address for non-digital
photos. After the FWC verifies the sighting, it will be
reported to the USDA/APHIS/WS and shared with
other agencies and groups working to deal with the
growing problem of invasive wildlife in Florida.
In the coming years, Florida's scientists and
government agencies plan to organize and train
concerned citizens like you to create an official
network of volunteers that will help to rapidly detect,
report, and respond to new wildlife invasions. The
support of citizens who are concerned with protecting
Florida's native wildlife and ecosystems will be
critical to the development and success of this
network.
You can also help to alleviate the growing
numbers of non-native bird species in Florida by
being a responsible and educated pet owner. Never
set any pet free outside! Finally, you can also help by
learning more about invasive plants and animals and
their impacts on Florida's natural environment, and
by educating others. For more information on
Florida's introduced birds and how you can help, read
"Florida's Introduced Birds: An Overview"
(http://edis.ifas.ufl.edu/uw297), and check out the
Additional Resources listed below.
Additional Resources
There are a variety of online guides, books and
other publications that we recommend for additional
information on Florida's native and non-native
birds.
Books and Scientific Publications
Alsop, Fred J., Smithsonian Handbooks: Birds of
North America – Eastern Region. (New York: DK
Publishing, Inc., 2001).
Figure 8. Documented locations of introduced Sacred Ibis
(Threskiornis aethiopicus) sightings in Florida. Multiple
sightings in nearby areas are shown by a single larger dot
for ease of viewing. Check for new sightings of Sacred
Ibises (and other introduced species) in your area by
viewing the distribution maps on the Everglades
Cooperative Invasive Species Management Area website
at http://www.evergladescisma.org/distribution. Credit:
Monica McGarrity, University of Florida, 2009 (Data
source: Everglades Cooperative Invasive Species
Management Area) Credits:
Bull, J., and J. Farrand, Jr., The Audubon Society
Field Guide to North American Birds. (New York:
Alfred A. Knopf, 1977).
Clergeau, P., and P. Yésou, "Behavioural flexibility
and numerous potential sources of introduction for
the sacred ibis: causes of concern in western
Europe?" Biological Invasions 8 (2006): 1381-1388.
Herring, G., and D. E. Gawlik, "Potential for
successful population establishment of the
nonindigenous sacred ibis in the Florida Everglades,"
Biological Invasions 10 (2006): 969-976.
Kale, H. W. II, and D. S. Maehr, Florida's Birds.
(Sarasota: Pineapple Press, Inc., 1990).
Peterson, R. T., Peterson Field Guides, Eastern Birds.
(Boston: Houghton Mifflin Co., 1980).
Pranty, B., A Birder's Guide to Florida. (Colorado
Springs: American Birding Association, 1996).
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Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.
Florida's Introduced Birds: Sacred Ibis (Threskiornis aethiopicus)
Robbins, C. S., B. Bruun, H. S. Zim, and A. Singer, A
Golden Guide to Field Identification: Birds of North
America. (New York: Golden Press, 1983).
Sibley, D. A., The Sibley Field Guide to Birds of
Eastern North America. (New York: Knopf, 2003).
Williams, A. J., and V. L. Ward, "Sacred ibis and
gray heron predation of cape cormorant eggs and
chicks; and a review of ciconiiform birds as seabird
predators," Waterbirds 29 (2006): 321-327.
Yésou, P., and P. Clergeau, "Sacred Ibis: a new
invasive species in Europe," Birding World 18
(2005): 517-526.
Online
International Union for Conservation of
Nature—2009 IUCN Red List of Threatened Species.
Threskiornis aethiopicus—species account.
http://www.iucnredlist.org/apps/redlist/details/
144745/0
Florida Fish and Wildlife Conservation Commission
Non-Native Wildlife
http://myfwc.com/nonnatives/index.htm—click on
"Birds"
Everglades Cooperative Invasive Species
Management Area (ECISMA)
http://www.evergladescisma.org
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